1. Field of the Invention
The invention is generally related to the area of optical communications. In particular, the invention is related to optical devices, modules or assemblies to process light beams and the making thereof. The optical devices modules or assemblies include, but may not be limited to, multiplexing devices and adding/dropping devices.
2. The Background of Related Art
The communication networks continue to demand increasingly bandwidths and flexibility to different communication protocols. Fiber optic networks are becoming popular for data transmission due to their high speed and high capacity capabilities. Wavelength division multiplexing (WDM) is an exemplary technology that puts data from different sources together on an optical fiber with each signal carried at the same time on its own separate light wavelength. Using the WDM system, separate wavelengths or channels of data can be multiplexed into a light stream transmitted on a single optical fiber. To take the benefits and advantages offered by the WDM system, there require many sophisticated optical network elements.
Optical add/drop devices are those elements often used in optical systems and networks. For example, an exchanging of data signals involves the exchanging of matching wavelengths from two different sources within an optical network. In other words, the multi-channel signal would drop a wavelength while simultaneously adding a channel with a matching wavelength at the same network node.
From a terminology viewpoint, a device that multiplexes different wavelength channels or groups of channels into one fiber is a multiplexer, and a device that divides the multiplexed channels or groups of channels into individual or subgroups of channels is a demultiplexer. Specifically, a multiplexer combines several channels of optical signals into a single signal, or in reverse a demultiplexer separates a single multichannel signal into several individual channel signals, such multiplexer or demultiplexer is referred to a multiplexing or demultiplexing module, or simply multiplexer or demultiplexer.
Multiplexers/De-multiplexers (Mux/DeMux) are needed in optical modules such as quad small-form-factor pluggable (QSFP). The QSFP is a full-duplex optical module with four independent transmit and receive channels. It is designed to replace four single-channel small-form-factor pluggable (SFP) and in a package only about 30% larger than the standard SFP. To equip such an QSFP, the size of a Mux/DeMux module into a QSFP, the size of the module is very important. Accordingly, there is a great need for such optical modules being made small, and at the same time, the modules so designed are amenable to small footprint, broad operating wavelength range, enhanced impact performance, lower cost, and easier manufacturing process.